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[[File: | [[File:Ephapsis 2.jpeg|center|frame|'''Figure 2:''' Proposed mechanisms for electrical transmission. '''(A)''' The cartoon illustrates the hypothetical current flow generated by an action potential approaching a synaptic terminal (top) and at the synaptic terminal itself (bottom). The initial anodal effect (A1) is followed by a cathodal effect (C2) in the postsynaptic membrane directly facing the presynaptic terminal. '''(B)'''Early electrical theory of inhibition. Cartoon illustrates the current flow through the synaptic terminal of an interneuron (G) on a postsynaptic cell (M). To exert an inhibitory action, the interneuron should receive subthreshold stimulation by its afferent input (I). An excitatory input (E) into the postsynaptic cell is also represented. Reproduced from Eccles (1982), with permission.]] | ||
Finally a set of elegant experiments by Katz, Fatt, Miledi and colleagues showed that chemical transmission is mediated by a Ca++-dependent electrically regulated form of release of neurotransmitter packets (Katz, 1969), which in turn are capable of generating an electrical signal in the postsynaptic cell by acting specifically on ligand-gated ion channels known as “receptors” (Figure1B, left). It is now recognized that both modes of communication, electrical and chemical, are operative (Figure 1B). | Finally a set of elegant experiments by Katz, Fatt, Miledi and colleagues showed that chemical transmission is mediated by a Ca++-dependent electrically regulated form of release of neurotransmitter packets (Katz, 1969), which in turn are capable of generating an electrical signal in the postsynaptic cell by acting specifically on ligand-gated ion channels known as “receptors” (Figure1B, left). It is now recognized that both modes of communication, electrical and chemical, are operative (Figure 1B). |
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